Would it be possible to just get a sensor for a '97 silverado, like where the vortec motor was originally from? Or wouldn't that match up with the factory wiring (I'm fine with splicing in a different fitting, but I do want it to actually work good).

By the way, all I'm talking about is an "idiot light" setup. I don't have a fancy temp gauge in my base malibu.

Thanks for the help so far, guys!

Resistance values from a 1997, are way different from a 1971.

You need to use the stock sender from the 1971 application. This will work correctly with your dash 'light'/gauges.